Nano-structure printing process could thwart bank-note fakers

The breakthrough, detailed in a paper published in the Journal of Advanced Functional Materials, represents an advance in the field of structural colour printing, whereby structured nanomaterials are used to render colours.

The Glasgow technique allows the ‘printing’ of two entirely different, but highly detailed, full-colour images within the same surface area, something which the group claims has never been done before using ‘structural colour’ techniques. This has been achieved by the development of special nano-scale plasmonic colour filters that display different colours depending on the orientation of the light which hits it.

The team’s breakthrough comes from including an additional nanoscale element in the structural colour process, created at the University’s James Watt Nanofabrication Centre.

Lead author of the paper Dr Alasdair Clark said: “We’ve discovered that if we make colour pixels from tiny cross-shaped indents on a strip of aluminium film, the colour they display becomes polarisation-dependent, allowing us to encode two colours into a single pixel, and then select which colour is displayed by shining different polarisations of light at the surface. By changing the size and shape of the nanoscale indent, we can create a wide range of different colours at very high resolutions.”